Wasteful killing in urban black widows:  gluttony in response to food abundance

My name is Trish Trubl and I started working in Dr. J’s lab in May of 2007 and obtained a SOLUR research fellowship to support my work throughout my senior year.  I have since graduated and begun graduate work as a M.S. student with Dr. J as my advisor.  Below is the abstract from the independent research project I completed as an undergraduate. 

Wasteful killing, the partial consumption and/or abandonment of prey, is a perplexing phenomenon because the costs of this behavior seem so high (e.g. energetic loss, risk of injury). Wasteful killing in spiders has received much attention because spiders are key predators assumed to be limited by prey availability. We investigated the conditions in which a web-building spider, the North American black widow (Latrodectus hesperus) participates in wasteful killing. Using a repeated measures design across the adult life cycle of thirteen female black widows collected from urban habitats throughout Phoenix, AZ, we measured each spider’s foraging voracity and wastefulness after varied periods of food restriction (2, 7, and 14 days). Our results showed that black widows killed fewer prey and were more wasteful with those prey when food restriction was relaxed (i.e. 2 days of restriction) relative to higher levels of food restriction (7 and 14 days).  While food restriction did decrease body condition, condition alone was a poor predictor of voracity and wasteful killing.  Thus, voracity and wasteful killing were not repeatable for individuals across their lifespan, and therefore appear unlikely to be correlated across contexts with other aggressive traits as a behavioral syndrome. We discuss other possible benefits for wasteful killing in the contexts of intraspecific competition and mate attraction.

My goal is to follow this work up in my Masters to look more comprehensively at the behavior, ecology and evolution of foraging behavior in urban and desert black widows.